KVM: x86: Test case for TSC scaling and offset sync

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20220225145304.36166-4-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 03662666b30df16f7f021562d292298baba41f7b..c9cdbd24872766dd696487f91022d99c1feb634e 100644 (file)
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -66,6 +66,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_int_ctl_test
+TEST_GEN_PROGS_x86_64 += x86_64/tsc_scaling_sync
 TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
 TEST_GEN_PROGS_x86_64 += x86_64/userspace_io_test
 TEST_GEN_PROGS_x86_64 += x86_64/userspace_msr_exit_test

diff --git a/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
new file mode 100644 (file)
index 0000000..f0083d8
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * svm_vmcall_test
+ *
+ * Copyright © 2021 Amazon.com, Inc. or its affiliates.
+ *
+ * Xen shared_info / pvclock testing
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+
+#include <stdint.h>
+#include <time.h>
+#include <sched.h>
+#include <signal.h>
+#include <pthread.h>
+
+#define NR_TEST_VCPUS 20
+
+static struct kvm_vm *vm;
+pthread_spinlock_t create_lock;
+
+#define TEST_TSC_KHZ    2345678UL
+#define TEST_TSC_OFFSET 200000000
+
+uint64_t tsc_sync;
+static void guest_code(void)
+{
+       uint64_t start_tsc, local_tsc, tmp;
+
+       start_tsc = rdtsc();
+       do {
+               tmp = READ_ONCE(tsc_sync);
+               local_tsc = rdtsc();
+               WRITE_ONCE(tsc_sync, local_tsc);
+               if (unlikely(local_tsc < tmp))
+                       GUEST_SYNC_ARGS(0, local_tsc, tmp, 0, 0);
+
+       } while (local_tsc - start_tsc < 5000 * TEST_TSC_KHZ);
+
+       GUEST_DONE();
+}
+
+
+static void *run_vcpu(void *_cpu_nr)
+{
+       unsigned long cpu = (unsigned long)_cpu_nr;
+       unsigned long failures = 0;
+       static bool first_cpu_done;
+
+       /* The kernel is fine, but vm_vcpu_add_default() needs locking */
+       pthread_spin_lock(&create_lock);
+
+       vm_vcpu_add_default(vm, cpu, guest_code);
+
+       if (!first_cpu_done) {
+               first_cpu_done = true;
+               vcpu_set_msr(vm, cpu, MSR_IA32_TSC, TEST_TSC_OFFSET);
+       }
+
+       pthread_spin_unlock(&create_lock);
+
+       for (;;) {
+               volatile struct kvm_run *run = vcpu_state(vm, cpu);
+                struct ucall uc;
+
+                vcpu_run(vm, cpu);
+                TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+                            "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
+                            run->exit_reason,
+                            exit_reason_str(run->exit_reason));
+
+                switch (get_ucall(vm, cpu, &uc)) {
+                case UCALL_DONE:
+                       goto out;
+
+                case UCALL_SYNC:
+                       printf("Guest %ld sync %lx %lx %ld\n", cpu, uc.args[2], uc.args[3], uc.args[2] - uc.args[3]);
+                       failures++;
+                       break;
+
+                default:
+                        TEST_FAIL("Unknown ucall %lu", uc.cmd);
+               }
+       }
+ out:
+       return (void *)failures;
+}
+
+int main(int argc, char *argv[])
+{
+        if (!kvm_check_cap(KVM_CAP_VM_TSC_CONTROL)) {
+               print_skip("KVM_CAP_VM_TSC_CONTROL not available");
+               exit(KSFT_SKIP);
+       }
+
+       vm = vm_create_default_with_vcpus(0, DEFAULT_STACK_PGS * NR_TEST_VCPUS, 0, guest_code, NULL);
+       vm_ioctl(vm, KVM_SET_TSC_KHZ, (void *) TEST_TSC_KHZ);
+
+       pthread_spin_init(&create_lock, PTHREAD_PROCESS_PRIVATE);
+       pthread_t cpu_threads[NR_TEST_VCPUS];
+       unsigned long cpu;
+       for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++)
+               pthread_create(&cpu_threads[cpu], NULL, run_vcpu, (void *)cpu);
+
+       unsigned long failures = 0;
+       for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++) {
+               void *this_cpu_failures;
+               pthread_join(cpu_threads[cpu], &this_cpu_failures);
+               failures += (unsigned long)this_cpu_failures;
+       }
+
+       TEST_ASSERT(!failures, "TSC sync failed");
+       pthread_spin_destroy(&create_lock);
+       kvm_vm_free(vm);
+       return 0;
+}